Although we live in a world that glorifies self-belief and stigmatizes self-doubt, there are really only two advantages to thinking that you’re better than you actually are. The first is when you’re attempting to do a difficult task. Believing that you can do something difficult is half the battle, but if you truly overrate your abilities, then by definition you will fail. The second is fooling others into thinking that you are competent. Most people will be found out eventually, and the personal benefits of faking competence will be offset by the negative consequences for others. For example, deluded leaders may come across as charismatic and talented, but their overconfidence puts their followers at risk in the long run. In contrast, when leaders are aware of their limitations, they are less likely to make mistakes that put their teams, organizations, and countries in danger.

And yet — as I demonstrate in my latest book — leaders are not generally known for their self-awareness. Although leadership talent is normally distributed, 80% of people think they are better-than-average leaders. Moreover, with narcissism rates rising steadily for decades, there is no reason to expect future leaders to be more accurate in their self-evaluations, let alone to be humble. Strengths-based coaching, and removing negative feedback from performance appraisals are aggravating the problem, validating leaders’ fantasized talents much like when parents tell their children that they are the brightest and cutest in the world. This is especially likely when leaders are intimidating, or when they surround themselves with sycophantic employees. As a result, leaders are deprived of the very feedback they need to get better.

Whether you manage or coach leaders, or are just trying to provide some feedback to your own boss, here are three simple points you may wish to consider in order to have this difficult (but necessary) conversation with them:

Tap into their personal motives: Nobody likes to be criticized — especially high-status individuals. However, if you can help leaders understand how they can achieve their personal goals, they will pay attention. The most effective way of doing this is by tapping into the leader’s motives and values. For instance, leaders who are driven by recognition care a great deal about their reputation. Telling them that they are seen as less capable than they think they are will probably mobilize them, even if you allow for the possibility that their reputation is unwarranted. On the other hand, when leaders are driven by power, you will be able to appeal to them by linking the feedback to their performance and career progression: “If you change X and Y, you will be able to outperform your competitors and make it to the top”. In contrast, when dealing with altruistic leaders, your best strategy for delivering negative feedback is to convey that “by changing X and Y, you will be able to harness your team’s potential and improve their engagement and wellbeing”.

Let the data do the talking: Leaders are not always interested in people, and they often regard psychological matters as fluffy. On the upside, they tend to care about results. A good way to help leaders understand that their self-views and behaviors matter is via 360-degree feedback (360s) and employee engagement In particular, there is ample evidence for the connection between 360s and leadership performance, as well as a leader’s integrity. The use of 360s also enhances coaching and development interventions by closing the “blind-spots” between leaders’ self-views and other people’s views on them. As for engagement, it is arguably the best source of data to evaluate leaders’ effectiveness — other than actual team performance data. For example, a meta-analysis of almost 8,000 business units and 36 organizations shows that increases in employee engagement are associated with better business-unit outcomes, including revenues and profits. Another data-driven approach to making leaders aware of their potential deficits is through scientifically valid personality assessments. When reports focus not just on the bright side, but also the dark side of personality, leaders will be able to understand what their “toxic assets” are. Indeed, dark side personality traits predict leader derailment even in the presence of outstanding technical skills and expertise. From Dominic Strauss-Kahn to Bernie Madoff, there is no shortage of famous case studies demonstrating that brilliant leaders can damage their own and others’ careers when they overuse certain strengths and are unable to tame their undesirable qualities.

Highlight the downside of self-confidence: A final point to consider is that leaders who are interested in science may be easily persuaded of the virtues of modesty, as well as the adverse consequences of hubris. In other words, there is vast empirical evidence to convince leaders that excessive self-confidence is more problematic than they think. For example, economic studies suggest that overconfidence leads to poor financial decisions and an inability to attend to social cues that highlight one’s mistakes. Financial studies show that overconfidence drives Forbes 500 CEOs to “persistently fail to reduce their personal exposure to company-specific risk”. Business studies show that overconfident entrepreneurs are not just more likely to fail, but also die younger than their more insecure counterparts. By the same token, there is also compelling evidence for the benefits of (moderate) self-doubt. For instance, academic studies suggest that leaders who underrate their abilities tend to be more effective, and broad theories of motivationsuggests that self-perceived deficits in competence are pivotal for improving one’s performance. Perhaps most famously, Jim Collins’ seminal analyses of effective executives suggested that the most outstanding leaders are not just relentless and driven, but also humble.

Sadly, these suggestions are not always easily applied. For example, leaders with poor 360s tend to dismiss the value of feedback, which makes them virtually uncoachable. This is one of the fundamental limitations of coaching: it often works with those who need it the least; but it works a lot less with those who need it the most. There are also too many sources of (fake) positive feedback at the disposal of leaders, no matter how talented they are. In that sense, the world of work is not so different from Facebook, though even Facebook has decided to allow users to leave negative feedback on other people’s posts. Ultimately, we need to get better at selecting leaders who are comfortable with their own insecurities and self-doubt. As the great Voltaire noted: “Doubt is not a pleasant condition, but certainty is absurd.”